Improvements in the field of telephony during the last quarter century have permitted an increasing number of telephone calls to be served on a fully or partially automated basis. These improvements have resulted in better customer service, while at the same time allowing more economical provision of telephone services.
The automation of certain types of telephone services, e.g., coin pay calling, requires the provision of automatically generated announcements. Early announcement generating equipment generally comprised a plurality of magnetic tape read-back units, each of which stored an entire announcement. In order to treat the diverse number of situations which can occur in the course of providing automated special phone services, it is desirable to provide storage not for complete announcements but for individual speech segments which can be selectively combined to make a great number of announcements. Early systems of this type incorporated a number of analog magnetic playback units, each associated with a particular speech segment or word. An announcement was then obtained by switching between these various playback units in order to assemble a completed message. Such analog storage requires a great deal of hardware and is susceptible to faults. More recent systems have adopted techniques which employ the digital storage speech segment information. These systems have generally included a rotating memory, e.g., a disc, on which a plurality of sequential word locations are used to store digital information required to make up a speech segment. A message can be assembled by selectively accessing these segments. The present invention avoids the use of rotating storage device and is thereby physically smaller and less susceptible to mechanical failure.